Lost hope? My soul is deteriorating!

I am 20 years old. DH is 25. I'm a bit overweight. He's healthy. We have been TTC for 7 months. We DTD every day some months during my fertile window and some months every other day. I'm starting to lose hope. My sister is on baby #3 and she's 21. My life is together and I'm financially ready. I'm so discouraged. Every month I feel like I see maybe a faint line, then Aunt Flo makes sure to put me in check that I'm not pregnant. I try to avoid any baby conversations between my sister and mom. I've taken myself away from my family. Just hurt, angry, and emotional. Plus it doesn't help when my mother in law calls me fat continuously over text and she hopes I die during child birth plus she doesn't want anything to do with it. ???? I'm just a mess right now and I feel like giving up. 
​P.s- my DH sister has a 12 year old girl and his mom adores her. And she doesn't know her father. Uggghhhhhhhhhhh ? I'm so confused.